[o11c]

There are 4 main name forms that I often see:

* Full name (John Smith)

* Index name (Smith, John) - mostly for meatspace compatibility.

* Preferred name (John Smith) - used in lists with other people's names

* Personal name (John) - used in direct communications

[djur]

Index vs. preferred name can get a bit wonky. I used to work on software that had a lot of attendee/speaker list functionality. Different types of customer had strong expectations about how names should be displayed and ordered, sometimes even in different contexts (attendees might be listed by last name but speakers by first, etc.). We had medical conferences where everybody would be listed as "Dr. Fredrica Bloggs, MD" but the sort order would be by last name. And that was just for English-speaking customers.

[kyleee]

it is really something to be dealt with via locale settings but the lack of standardized data underlying what the locale logic would display really throws a wrench in things

[jltsiren]

The name used in direct communications can depend on the level of formality and on the context. For example, John / Mr. Smith / Dr. Smith.

Then there is the difference between the "full" name and the legal full name, with all names spelled out. The latter is sometimes necessary, but it can be awkward or inappropriate to use it in most places that expect a full name.